Throttle control



Nov. 22, 1966 w. s. SCHOEPPACH 3,

THROTTLE CONTROL Filed Oct. 20, 1964 IN VENTOR.

5 05/06 5 hioepfdc) A T TORNEY United States Patent 3,287,007 THROTTLE CONTROL Wayne S. Schoeppach, Mount Morris, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 20, 1964, Ser. No. 405,034 4 Claims. (Cl. 267-1) This invention pertains to an internal combustion engine throttle control and particularly to a control unit which acts both as an idle speed governor to maintain an appropriate engine idling speed and as a throttle return check to prevent rapid closure of the throttle valve.

The provision of a control to maintain engine idling speed has become of increasing importance. The modern automobile includes a number of accessory devices, such as air conditioning systems and power steering assists, which are driven from and impose a load upon the engine. When these device are operated while the engine is idling, the load slows the engine and may cause it to stall. This invention provides a control which senses the increase in engine load and opens the throttle to increase engine speed sufficiently to prevent stalling.

The desirability of a control to slow the final closing movement of the throttle 'has been recognized for a number of years. During open throttle engine operation, fuel vapor condenses on the walls of the intake manifold. If the throttle is suddenly closed causing a sharp increase in manifold vacuum, the condensed fuel is swept into the engine, resulting in an overrich mixture which may stall the engine. This invention provides a control which slows the final closing movement of the throttle to allow manifold vacuum to increase gradually enough that condensed fuel is not swept into the engine.

The controls provided by this invention are combined in a single unit which is improved in several respects over the unit invented by Elmer Olson and disclosed in United States Patent 2,782,025. These improvements are discussed below.

The details as well as other objects and advantages of this invention are disclosed in the following description and in the drawing in which:

FIGURE 1 is a view of the throttle control unit mounted on an engine;

FIGURE 2 is an enlarged sectional view of the control unit; and

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2.

Referring to FIGURE 1, an internal combustion engine is indicated by numeral and has a carburetor 12 mounted on the intake manifold 14 thereof. Carburetor 12 includes a throttle valve 16 mounted upon a rotatable throttle shaft 18. A throttle lever 20 is secured to throttle shaft 18 and is provided with an opening 22 to which the customary throttle rod (not shown) may be connected for operating the throttle in a conventional manner, such as by an accelerator pedal. The throttle control unit 24 is mounted on carburetor 12 by a bracket 26.

Referring now to FIGURE 2, throttle control unit 24 includes a flexible diaphragm 28 clamped between a pair of housing members 30 and 32 to form a pair of chambers 34 and 36. A conduit 38 is connected to intake manifold 14, and, through an opening 40 in housing member 32, subjects chamber 34 to manifold vacuum. An opening 42 in housing member 30 maintains chamber 36 at atmospheric pressure. Thus, during engine operation, the pressures against diaphragm 28 pull it toward the right as viewed in the drawing. A spring 44 resists this movement.

A plunger 46 is secured to and moves coincidentally with diaphragm 28. An atmospheric vent passage 48, ex-

ice

tending through plunger 46, is controlled by a valve 50 adapted to coact with a seat 52 formed in passage 48. A spring 54 seats upon a ledge 56 within plunger 46 and upon a flange 5-8 formed about the stem 59 of valve 50 to bias valve 50 in a valve opening direction. Thus atmosphere may enter chamber 34 by passing along the scalloped edges of stem 59 and then through passage 48.

A head 60 if formed upon stem 59 and contacts throttle lever 20 in the closed throttle position. Spring 54 should be sufliciently weak that the customary throttle return spring 61 (FIGURE 1) while pushing throttle lever 20 against head 60, causes valve 50 to seat on 52 and close atmospheric vent 48.

This construction operates as a throttle return check in the following manner:

As the throttle is opened, throttle lever 20 is rotated away from head 60 of valve 50 and valve 50' is opened by spring 54 to bleed atmosphere through vent 48 to chamber 34, reducing the vacuum therein. Spring 44 then pushes the assembly of diaphragm 32, plunger 46, and valve 50 to the left to fol-low throttle lever 20. The assembly is thus extended to meet throttle lever 20, and upon closing of the throttle, throttle lever 20 contacts head 60 of valve 50 and compresses spring 54 so that valve 50 closes vent 48, allowing the pressure in chamber 34 to be reduced. A restriction 62 in opening 40 permits a gradual reduction of the pressure in chamber 34, or conversely, a gradual increase in the vacuum in chamber 34, so that diaphragm 32 is slowly drawn toward the right. Throttle lever 20, under the action of throttle return spring 61, follows this movement of the assembly and gradually closes throttle valve 16.

Those skilled in the art will recognize as an improvement in the operation of this throttle return check that during all open throttle operation, the assembly is extended to meet throttle lever 20. This occurs because chamber 34 is subjected to atmospheric pressure through vent 48 until throttle lever 20 closes valve 50. In the prior art, the throttle return check of such a combined unit is not effective unless the intake manifold is at a vacuum lower than idle vacuuma situation which does not exist during steady state highway driving. The throttle return check of such a prior art combined unit is therefore not effective upon a sudden deceleration from steady state road load operation.

The unit provided by this invention also constitutes an improvement over the prior art since it requires no carefully machined and matched parts of the throttle return check. A lower cost of the unit is thereby achieved.

This construction operates as an idle speed governor in the following manner:

During idle throttle lever 20 is pulled against head 60 of valve 50 under the action of throttle return spring 61 and spring 54 is compressed so that valve 50 closes vent 48. Chamber 34 is thus maintained at engine vacuum. Should a reduction in engine speed occur, engine vacuum will drop and the assembly will be moved toward the left by spring 44. Throttle lever 20 will be rotated to open throttle valve 16 slightly and increase the engine speed. Should the engine speed increase from a normal idling speed, engine vacuum will increase and diaphragm 32 will move toward the right. Throttle lever 20, biased by the throttle return spring, follows the assembly and closes throttle valve 16 slightly. Restriction 62 in opening 40 prevents rapid fluctuations in engine vacuum from occurring in chamber 34, thus preventing rapid opening and closing of throttle valve 16 and uneven engine operation.

It will be appreciated that this construction compensates for the load placed on the engine by accessory devices, such as the refrigerant compressor of an air conditioning system or the pump of a power steering system. During operation of these systems the engine idling speed may be slowed, but as indicated above, the assembly will open the throttle valve to increase engine speed and prevent stalling.

The idle speed governor operation of this unit is more efiicient than that of the prior art combinedunits because it 'has no tendency to hunt. Restriction 62 in opening 40 to chamber 34 modulates and averages fluctuations in the vacuum communicated to chamber 34 to prevent hunting of the diaphragm. In the prior art units the diaphragm must respond instantaneously to a reduction in manifold vacuum in order to function as a throttle return check. Those units therefore must be sensitive to changes in manifold vacuum and may cause uneven engine operation in some instances.

This unit is additionally advantageous in that the conventional throttle stop may be eliminated, head 60 acting in its place. The prior art units have been effective to open the throttle during low vacuum engine operation but,

because of their tendency to hunt, have not been suflicient-ly efiective to control all substantially closed throttle operation without a throttle stop. Elimination of the throttle stop contributes a small amount toward reduction of overall engine cost.

This unit may also operate as a hot idle and an altitude compensator. Should the engine idling speed decrease during hot operation due to a decrease in air density or an increase in the amount of fuel vapor fed to the engine, the assembly will open the throttle valve slightly to increase the idling speed.

In appropriate situations, this unit may be calibrated in a manner whereby adjustments of the idling speed during break-in of the engine will be unnecessary, the idle speed governor control automatically providing this adjustment. Additionally, the unit may be able to adjust the idling speed sufficiently during cold engine operation that the customary fast idle cam could be eliminated. Further it is thought that this unit will prevent carburetor icing stalls.

It will be recognized, therefore, that this unit constitutes a throttle movable between open and closed positions to vary engine speed and having independent means for moving said throttle, comprising a pressure-responsive memher adapted to be connected with said throttle to control said throttle near its closed position, means to apply en-. gine vacuum against said member in a throttle closing direction, means biasing said member in a throttle opens ing direction, and means to admit atmosphere against said member in a throttle opening direction only when said throttle is opened by said independent means.

2. A control for an internal combustion engine having a throttle movable between open and closed positions to vary engine speed and having independent means for moving said throttle, comprising a pressure-responsive member adapted to be connected with said throttle to control said throttle near its closed position, means to apply engine vacuum against said member in a throttle closing direction, means biasing said member in a throttle opening direction, said member having a passage through which atmosphere may be applied thereagainst in a throttle opening direction, a valve in said passage, means biasing said valve in a valve opening direction, and means to close said valve when said member is connected with said throttle.

3. A control for an internal combustion engine having a throttle movable between open and closed positions to vary engine speed, comprising a member adapted to contact said throttle to control said throttle near its closed position, a plunger having a passage in which said member is supported, said passage including a valve seat, a valve formed on said member adapted to coact with said uum chambers, said plunger being secured to and extending through said diaphragm with said passage opening into said vacuum chamber, said housing having an inlet through which said vacuum chamber may be subjected to engine vacuum, and means biasing said .dia-: phragm and plunger in a valve closing and throttle opening direction.

4. The control of claim 3 wherein said inlet is restricted to prevent hunting of said diaphragm caused by rapid fluctuations in engine vacuum.

No references cited.

MARK NEWMAN, Primary Examiner.

L. M. GOODRIDGE, Assistant Examiner. 

1. A CONTROL FOR AN INTERNAL COMBUSTION ENGINE HAVING A THROTTLE MOVABLE BETWEEN OPEN AND CLOSED POSITIONS TO VARY ENGINE SPEED AND HAVING INDEPENDENT MEANS FOR MOVING SAID THROTTLE, COMPRISING A PRESSURE-RESPONSIVE MEMBER ADAPTED TO BE CONNECTED WITH SAID THROTTLE TO CONTROL SAID THROTTLE NEAR ITS CLOSED POSITION, MEANS TO APPLY ENGINE VACUUM AGAINST SAID MEMBER IN A THROTTLE CLOSING DIRECTION, MEANS BIASING SAID MEMBER IN A THROTTLE OPENING DIRECTION, AND MEANS TO ADMIT ATMOSPHERE AGAINST SAID MEMBER IN A THROTTLE OPENING DIRECTION ONLY WHEN SAID THROTTLE IS OPENED BY SAID INDEPENDENT MEANS. 